JPH0354036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for coating a welding rod core wire with flux.

[Conventional technology and problems]

In the coated welding rod manufacturing process, a wet-kneaded flux adjusted to the desired composition is applied around the core wire, and then sent to a drying process to be dried and, if necessary, fired to form a coated welding rod. However, in this coating process, it is necessary for the flux to be coated uniformly around the core wire with sufficient adhesion strength, but in practice various problems are encountered. This will be explained based on Fig. 5, which shows an overview of flux coating. After selectively mixing powders of various metal oxides, silicic acid compounds, carbonates, etc., they are kneaded with water glass and the wet-mixed flux is transferred to a molding machine. A cylindrical flux 2 is formed, and the receiving part 4 of the coating machine 1 is
(Separate top and bottom structure). This is made into one lot, pushed into the flux cylinder 5 by the piston 6 of the hydraulic cylinder (the figure shows the cylindrical flux being pushed in), pressurized, and pushed out from the die 9 of the die head 8. At the same time, feed 3 cores into 1 from the core wire feeder.
The core wires are supplied one by one to the die head 8 via the guide 10, and extruded from the die head with a constant thickness of flux coated around the core wire. Cord wire 3 until pressure extrusion of flux 2 for one lot is completed.
The supply of the flux is carried out sequentially and continuously, and when the extrusion limit is reached, the flux pressurization and the core wire supply are stopped, the piston 6 returns to the starting position, and the cylindrical shape of the next lot is waiting on the side of the receiving part 4. The flux is set in the receiving part 4, and the above-mentioned pressure extrusion operation is repeated again. As shown in the figure, this conventional cylindrical flux 2 has a simple cylindrical shape with both end surfaces perpendicular to the longitudinal direction, and therefore the tip surface A and die head 8 of the present rotary rod are moved forward by the piston 6 at the start of painting. The remaining rear end surface B of the flux 7 from the previous lot shortens the distance while maintaining a parallel state, and instantaneously comes into contact with it to begin painting. The echo existing in the space between end face A and end face B will be discharged to the outside from the air vent groove 12 formed between cylinder 5 and die head 8 as end face A moves forward. When end face B comes into contact with end face A, the air is discharged from end face A.
A situation may occur in which air cannot keep up with the advance of the flux, and air remains between the end surfaces A and B and is compressed and mixed into the flux. This poses problems both in the advancing speed of the end face A and also in the shape of the cylindrical flux in which the end faces A and B are in simultaneous contact over the entire surface. Therefore, even if the speed of the piston 6 is reduced only at the time when the end surfaces A and B come into contact, it will only reduce the operating rate and will not be a complete solution. If air exists in the flux, the flux 2 is added around the core wire 3 using the die 9.
When applying the material, good pressure bonding cannot be performed, and it becomes difficult to form a coating with a uniform thickness. Furthermore, the surrounding pressure of the coated welding rod that has passed through the die 9 and exited from the coating machine changes dramatically from high pressure to atmospheric pressure, causing the air in the coating flux layer to expand rapidly, causing peeling of the flux layer and cracking of the coating. etc. will occur.

[Means and actions to solve the problem]

The present invention solves the above-mentioned problems of the conventional technology, and does not reduce the operating rate of the coating machine.
It is an object of the present invention to provide a flux coating method for a coated welding rod that can avoid air mixing into the flux at the time of starting coating by a simple means.

The gist of the present invention to achieve this object is that when a piston presses one lot of cylindrical flux loaded into a coating machine to coat a welding rod core wire, the piston-side end surface of the cylindrical flux,
This flux coating method for a coated welding rod starts coating by forming at least one of the end faces on the die head side into a convex shape and pressing it against the end face of residual flux from a previous lot. The present invention will be explained below based on specific examples shown in the drawings.

FIG. 1 is a longitudinal sectional view of a coating machine showing a coating state according to the present invention. The same parts as in FIG. 5 are given the same reference numerals. As is clear from the figure, in this example, the shape of the cylindrical flux 21 for one lot is formed so that the end face on the die head side, that is, the tip face A ₁ is convex, and the end face on the piston side, that is, the rear end face is formed into a convex shape in this example, and the end face on the piston side, that is, the rear end face is formed in a conventional manner. The shape is formed on a plane perpendicular to the longitudinal direction of the street. When the tip surface A ₁ of the cylindrical flux 21 is formed into a convex shape in this way, the tip surface A ₁ of the cylindrical flux 21 that is pushed forward by the piston 6 at the start of painting and the residual flux 7 from the previous lot are The distance between the end surfaces A ₁ and B 1 gradually narrows, and the air present in the distance is pushed out from the air vent groove 12 , and finally both end surfaces A ₁ and B ₁ come into partial contact, but at this point ( The behavior of the air from the state shown in Figure 1 until the end surfaces A ₁ and B ₁ are integrated has the following characteristics. To explain this using _the air flow state diagram when both end surfaces A _{1 and} B ₁ are in contact as shown in _{FIGS .} This state of contact spreads from the center to the periphery, and finally reaches complete contact. At this time, the air sandwiched between both end surfaces A ₁ and B ₁ flows radially from the centers A ₁₀ and B ₁₀ to the outer peripheral portion E as shown by arrow D in FIG. 2, and as a result, both end surfaces A ₁ ,
All the air between B _{and 1} is discharged to the outside of the coating machine 1 from the air vent groove 12. This is both end faces A ₁ ,
B ₁ in partial contact with the air vent groove 1 from that part.
This method attempts to forcibly extrude the cylindrical flux 21 in the direction of the outer periphery E, and can be said to be a new method that is completely different from the conventional method of bringing the entire surfaces of both end surfaces A and B into contact at the same time. . As a function and effect, in the conventional method of simultaneously contacting the entire surface of both end surfaces A and B, air may remain in the center of the end surface, but in the present invention, the method first makes partial contact and then gradually brings the peripheral portion into contact. Air is discharged smoothly and no air remains between the two end faces.

As shown in Fig. 1, the amount of air between both end surfaces A ₁ and B ₁ at the time when both end surfaces A ₁ and B ₁ come into contact is smaller by the convex portion of end surface A ₁ , and therefore the speed of the piston 6 is specially slowed down. Even if this is not done, the air will not be discharged instantaneously and the air will be discharged sufficiently smoothly. That is, the drawbacks of the prior art can be overcome without reducing the operating rate of the coating machine.

can be given.

FIG. 3 shows another specific example of the present invention,
The difference from the specific example shown in FIG. 1 is that a convex portion formed on the end surface of the cylindrical flux is formed on the piston side end surface, that is, the rear end surface. In this case, as shown in the figure, the rear end surface _B2 of the residual flux of the previous lot in the die head 8 is a convex surface, and in the illustrated example, it is an arcuate surface.
The central apex B ₂₀ of the convex surface and the central portion A ₂₀ of the tip surface (a plane perpendicular to the longitudinal direction) of the cylindrical flux 22 of the current lot first partially contact each other, and then the contact state spreads in the peripheral direction. This state and the state of air discharge are the same as in the case of the specific example shown in FIG. 1 described above, and smooth discharge of air between both end surfaces A ₂ and B ₂ can be realized. In this case, the flux pressing surface of the piston 61 is a concave surface in order to maintain the convex shape of the rear end surface of the cylindrical flux 22.

In the specific example shown in Fig. 3, in addition to coating a cylindrical flux with a convex end face formed in advance into a coating machine, a conventional simple cylindrical flux is loaded into a coating machine and pressed with a piston whose flux pressing surface is concave. At this stage, the end surface of the cylindrical flux may be made convex. Either method may be used, but in the latter case, a piston equipped with an air bleed mechanism is used.

Other examples include the tip of a cylindrical flux,
In the case where both of the rear end surfaces are made convex, there may be variations such as making one a highly convex surface and the other a shallow concave surface. FIGS. 4a to 4d show typical examples of convex surfaces formed on the end faces of cylindrical fluxes. Figure a shows the end face of the cylindrical flux 23, similar to the specific example in Figure 1.
An example where A ₃ is also formed into an arcuate surface, b is an example where the end surface A ₄ of the cylindrical flux 24 is formed into a conical shape, c is an example where the end surface A ₅ of the cylindrical flux 25 is formed into a truncated cone shape,
d is an example in which the end face _A6 of the cylindrical flux 26 is sloped. Although these examples are examples in which a convex portion is formed on the front end surface of the cylindrical flux, it may be formed on the rear end surface or on both front and rear end surfaces as appropriate. Further, as the air vent groove formed between the flux cylinder and the die head, a well-known groove such as that disclosed in JP-A-56-134097 is sufficient. Furthermore, if the piston for pressing the flux is also provided with an air bleed mechanism, the mechanism disclosed in, for example, Japanese Utility Model Application Laid-Open No. 54-27117 may be applied.

〔Effect of the invention〕

As explained above, according to the coated welding rod coating method of the present invention, air can be easily and smoothly discharged from the air vent groove by simply making the end face of the cylindrical flux convex, and the air can be discharged into the flux. air contamination can be avoided. Moreover, since there is no need to reduce the piston speed, there is no need to reduce the operating rate of the coating machine. The present invention is most suitable as a coating method for coated welding rods and has great industrial value.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a specific example of the coating method of the present invention, Fig. 2 is a diagram showing the state of air flow when the end faces of the flux between the lots come into contact, and Fig. 3 is a diagram showing another specific example of the present invention. , FIGS. 4a to 4d are diagrams showing typical examples of convex surfaces formed on the end faces of cylindrical flux,
FIG. 5 is an explanatory diagram of a conventional coating method. 1, 11...painting machine, 2, 21, 22, 23,
24, 25, 26...Cylindrical flux, 7...
Residual flux of previous lot, A, A ₁ , A ₂ ,
A ₃ , A ₄ , A ₅ , A ₆ ...Top surface of the cylindrical flux, B, B ₁ , B ₂ ...Rear end surface of the residual flux in the die head.

Claims (1)

[Claims] 1. When applying one lot of cylindrical flux loaded in the coating machine with a piston to coat the welding rod core wire, at least one of the piston-side end surface and die head-side end surface of the cylindrical flux is formed into a convex shape. A flux coating method for coated welding rods, characterized in that coating is started by pressing the residual flux on the end face of the rod.